• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.12
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• pp.2065-2071
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• 2007

This paper suggests the harmonic effects on HTS(High Temperature Superconducting) power cable. HTS cable is regarded as not only one of the important countermeasure to supply high density power demand area, but also one of countermeasures greenhouse technology. However, with the development of digital society, the distribution line power is much contaminated with harmonics generated by various power electronic equipments. This paper describes how the HTS cable responds to the harmonic and increases AC losses caused by hysteresis phenomenon. EMTDC based harmonic simulation results are compared with AC loss measured values.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.05a
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• pp.321-324
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• 2001

The metal-oxide-semiconductor field-effect transistor(MOSFET) has undergone many changes in the last decade in response to the constant demand for increased speed, decreased power, and increased packing density. This paper has compared Micro-Tec with ISE-TCAD. This paper investigates LDD MOSFET using two simulators. Bias condition is applied to the devices with gate lengths 180nm. We have presented MOSF ET's characteristics such as I-V characteristic, electric field. and compared with Micro-Tec and ISE-TCAD.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.11
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• pp.1511-1518
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• 2014

Demand for high fuel efficiency and smart features of the vehicles, research has been intensified. Hence, research and development on electric power steering (EPS) system to replace the existing hydraulic steering system has been actively conducted. Permanent magnet motors are widely used in automotive applications due to their high power density and high efficiency. However, increasing price and limited production of rare-earth permanent magnets has recently prompted the auto parts makers to substitute permanent magnet motors by non- or less rare earth magnet motors. Switched reluctance motors SRMs), known as typical non-rare earth motors have simple structure, low manufacturing cost, and high reliability. This paper discusses design, modeling, simulation, and experimental verification of a prototype SRM drive for electric power steering system.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.302-302
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• 2000

This paper presents the measurement and correction of PCB alignment errors for PCB-manufacturing machines. The conventional PCB-manufacturing machine doesn't have enough accuracy to accommodate the demand for high-resolution circuit pattern and high-density mounting capacity of electronic chips. It is because of alignment errors of PCB loaded to the PCB-manufacturing machine. Therefore, this study focuses on the development of the system which is able to measure and correct alignment errors whit high-accuracy. An automatic optical inspection part measures the PCB alignment error using two cameras, and the high-accuracy 3-axis stage makes correct of these error. The operating system is run in the environment of Window 98 (or NT). Finally we implemented this system to PCB screen printer and PCB exposure system.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.560-564
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• 1996

In recently, annealing process of cold rolled sheet tend to change to continuous annealing process for improving qualify, saving yield. In the meantime as demand for various kind and small lot of products has been increasing, batch annealing has been appreciated for its small restriction for the operation. So, we tested on the effect for a hydrogen contents of atmospheric gas at annealing furnace. As a result of several investigation. We confirmed for the following characteristics ; improved productivity, uniform heating, improved surface quality, saving energy. Therefore, the use of hydrogen instead of nitrogen as the protective gas, combined with high convection in batch annealing furnaces, has shown that considerable increases in furnace output and material quality are attainable. Owing to the low density, high diffusion and reducing character of hydrogen, a better transfer resulting in uniform material temperatures and improved coil surfaces can be achieved.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.936-939
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• 2006

The pneumatic isolator is widely adopted for anti-vibration of precision measuring and manufacturing equipments. But, when the precision demand on anti-vibration is extreme or the load is moving, the performance of anti-vibration can not meet satisfaction. In these cases, as a complementary, active vibration suppression system can be added for advanced performance. In this paper, an active control system is presented, which uses electromagnetic actuators for vibration suppression. The anti-vibration characteristic of pneumatic isolator is analyzed for system modeling and actuator specifying. The modeling and the 3D dynamic simulation is performed for control system design. For the electromagnetic actuator design, the magnetic flex density and the current-force characteristic analysis are achieved.

• Journal of Biosystems Engineering
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• v.16 no.3
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• pp.290-297
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• 1991

For the efficient utilization of the solar thermal energy to overcome the time gap between to supply and demand, an efficient heat storage technique, especially high density-latent-heat storage system, is necessary. In this study, the performance of a panel type latent heat storage equipment during heat discharging process was analyzed theoretically and experimentally. In order to find out the performance of the system, computer simulation programs were developed by finite difference method. The governing equations were constructed by two dimensional heat conduction model with moving boundary. The results of the experimental and the theoretical analysis were reasonably well agreed. The efficiencies of the double pipe type and the panel type latent heat storage equipment were compared.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.271-272
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• 2018

As the supply and demand of natural aggregate becomes more difficult in the domestic construction site continuously, many studies related to the recycled aggregate produced in the construction waste are going on. However, because of the safety and performance of the recycled aggregate, it is not used as aggregate for the structure, and it is mainly used as a nonstructural material. In addition, as the "recycled aggregate quality standard" has been revised in 2017, quality standards for various properties of recycled aggregate have been adjusted, and production technology suitable for recycled aggregate quality standards for concrete is needed. In this study, to improve the quality of recycled aggregate, we applied multistage wind pressure treatment method to the existing recycled aggregate production facility and compared the density, absorption rate, particle size before and after recycled aggregate treatment. As a result, quality criteria in various properties were analyzed satisfactorily.

• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1626-1628
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• 1998

In reccent years the large capacity underground power transmission systems have been required gradually with the increasing demand of electric power, the increasing electric power system and the environmental limitations of an overhead transmission line in the city. But it is difficult to get the space for the underground power transmission lines because of complicated distributions of underground public facilities. But as the superconducting power cables have the large power transmission capacity, the high power transmission density, and low loss characteristics in comparison with a conventional cable, the necessity for their development are increasing. In this paper, the results of the conceptual design of HTS power cable is described.

• Korean Journal of Materials Research
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• v.23 no.2
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• pp.112-115
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• 2013

One of the most important characteristics of Mg alloys is the high ratio of strength to weight. This is why there is a high demand for applications with these alloys in the transportation industries to reduce the fuel consumption and to save energy. In addition, magnesium (and its alloys) is of considerable interest as a structural material, especially in the aerospace and automotive industries thanks to its low density. However, its major drawback is its high sensitivity to corrosion. Therefore, its use requires the application of a surface treatment. This study used a die-casted AZ91D Mg alloyand all the samples were annealed (in $120^{\circ}C$). The surface microstructure and phase distribution in thin-walled AZ91D magnesium components cast on a hot-chamber die-casting machine were investigated by optical microscopy and scanning electron microscopy. The reflectance differences in the bulk state comparison with the annealing state are caused by hydrogenation presence of the Mg layer under an oxidation surface layer.